There are 3 possible ways now for RK:

1) He is RJ

2) He is a friend of RJ

3) He is hunting RJ on his own

1) He makes is personal with Lennon and just says that he is a FRIEND not a friend of RJ. He wants to know if Lennon recognise him just to be sure that Lennon hasn't told to anybody and this to be sure that his identity is secure. In this care the conversation told us that Lennon is a friend of RJ but didn't met really met him. Or Lennon met someone who was playing RJ role.
He stays there after Lennon dies waiting for PJ to feel the man's sorrow when RK tells him that Lennon died.

2) Rk is just an accomplice of RJ and when he tells Lennon "i wish i had a friend..." is because he knows that failing to accomplish a RJ plan or being discoverd as an RJ associate means a terrible death by the Serial Killers hand. 

3) Robert Kirkland wants to get Red John on his own using his personal abilities and who knows maybe RJ did something to him like did with PJ (not that personal). He wants to be sure that Lennon hadn't recognised him and by knowing that he then knows that RJ doesn't know but RK had to kill Lennon because in any case in that moment RK is burned. Then procedes to erase Lennon for his own safety.
He has to kill him because he knows RJ will eventually kill him and then hunt down RK. Asking RJ name is useless because as soon as Lennon tells RJ or a RJ friend about RK... RK is a dead man.


I don't know who RJ is but Heller said whe saw him and that when we will know who he is it will be like "oooh... aaaah... really?" so it's a character of limitate relevance. 
I think is the the guy in the very first episode, the one with the skull tatoo on his arm (the same mask RJ had on his first meeting with PJ).
Also the age, the air, everything fit. 
The question is, has RJ to be a rich powerfull man? No, it is not necessary.
He is the leader of a setta. He has disciples. They died for him rather than betray him.
His power is not to be seen. I remind you to a speech of Devil's Advocate "your problem is that they see you coming. You are not a surprise. Learn not to be seen."
This is the reason. He has no interest on being caugt or suspected.
Bertram is similar to RJ but is a puppet. He is similiar by behaviour but it will be a decoy. Everybody looking in the wrong direction.

I think that Kirkland has nothing to do with Red John.
Do you remember Jane talking to Lennon before he was shot? Could it be the Jane hypnotized him so that Lennon said he worked for Red John. 
When Kirkland talks to Lennon in the hospital, he uses the same expression that Jane used.
I am not sure yet what all this means, but I think that Kirkland wanted to know if Lennon was clear or not. 
I think, Lennon never knew Red John. Jane wanted Lorelei to think that he knew RJ.

Also when Jane saw Lorelei dead he mentionned: "She had it coming". Why should he say that? Is it because she didn't say Red John's name? Because she killed Lennon?

I still suspect Walter Mashburn to be Red John. Who else would have so much influence on other people, especially women? He and Jane liked each other and also they like the same woman - Lisbon. It seemed like a game for Walter to get a date with her... just because he felt that PJ likes her so much.